Acid calcium tetraphosphate and method of making the same



Patented Oct. 18,1938

PATENT- OFFICE ACID CALCIUM TETBAPHOSPHATE AND METHOD OF MAKING THE SAME Augustus H. Fiske, Warren, E. L, assignor to Rumiord Chemical Works, Bumi'ord, R. 1., a. corporation of Rhode Island No Drawing. Application May 11-, 1937,

Serial No. 142,057

Claims.

' My present invention relates to a calcium or like tetraphosphate and'particularly to an acid 7 calcium tetraphosphate adapted for various uses,

but notably for use in connection with food prod- 5 ucts as in the leavening of bread doughs or sponge.

As in my previous patents, I desire again to give full credit to the prior work of others of recognized standing. My previous patent group related to a sodium. tetraphosphate for softening waters, and were granted currently in 1935, 1936 and 1937.

Therein I noted that Fleitmann and Henneberg had pioneered in the discovery of tetraphosphoric acid in 1846, and that such an acid was described by Roscoe and Schlorlemmers Treatise on Chemistry, published in 1905.

Tetraphosphoric acid and the tetraphosphates, as known prior to my present invention, were purely chemical curiosities except as developed for non-edible purposes as in mywater softening sodium tetraphosphates of my prior patents above referred to for use as soap savers in the cleansing industries and the like.

nets of my patents aforesaid, tetraphosphoric acid has become available commercially. This is in the nature of a rather syrupy liquid, which, upon analysis, I found usually contains approximately 17% of pyro or like phosphates.

application Serial No. 142,058 I described and claimed a process for purifying this commercial tetraphosphoric acid and the new pure acid as such produced by it.

cial tetraphosphate and my own purified tetraphosphate, led me to contemplate the use of one of them to give an acid calcium tetraphosphate of potentially high commercial value.

In my said researches I studied all of the indicated basic salts of such a tetraphosphoric acid in view of the possibility of producing commencially a useful calcium tetraphosphate. The men-- tral calcium salt, as precipitated from solution by Fleitmann and Henneberg in their chemical re.- search above acknowledged, never found practical placement in the industrial arts. When I first produced the acid calcium tetraphosphate, I realized that I had made a salt which, as far as I now know, had not even been previously de scribed.

This acid salt-has distinct practical possibilities and uses apparently unforseen due to the fact that it could not previously have been produced Since the commercial exploitation of the prod- In my copending My concurrent research with both the commencommercially. In following through with my concept, I produced flveol' these possible salts of calcium containing from one to flve equivalent molecules of calcium as follows:

C9.(I-I5P401a) 2 CaH4P401: Caz (H3P4O1a) 2 Carl-121 401: Gas (HP4013) 2 The addition oi the proportion of one-half an atom of calcium wasa failure. It gave a sticky syrupy material which was of no apparent particular commercial value even today, but may have important values on further research. I also made materials having the proportion of one atom and three atoms of calcium to two molecular proportions of the tetraphosphoric radical, but found them unpromislng according to present conditions. I also made a fourth material containing two atoms of calcium per one molecular portion of the tetraphosphate radical and found it to be very satisfactory and-to have proper physical properties available as an immediate commercial product. From this fourth I obtained an acid calcium tetraphosphate, which is a white pulverul'ent material and has a neutralizing value of 66% of its weight of bicarbonate of soda.

To check my result further I added the calculated proportion of another half an atom of calcium to the tetraphosphate radical and obtained a somewhat similar material but with a neutralizing value of approximately 50% of its weight 01' bicarbonate of soda.

Checking my then research further by the further addition 0! calcium Iobtained correspondingly new materials but of progressively lower and lower neutralizing value. This for current commercial prospects was so significant that I felt obliged to concentrate my efforts and limited laboratory resources to the above indicated material and its commercial production.

' My acid calcium tetraphosphate is prepared as follows:

I take a calculated amount of the tetraphosphoric acid and I mix with it a calculated amount of pure lime, the chemical formula of which is CaO, and since the tetraphosphoric acid requires additional waterto enter into the reaction I add a calculated amount of water to the other two reactants.

My formula for making my product is 20 parts. by weight of commercial concentrated tetraphos- This white material is my new substance and it has the formula CazH2P4Oia5HQO.

This material can be madein commercial quantitles and as stated above is a new substance never having been described in the chemical literature so far as I know.

My acid calcium tetraphosphate is an exact chemical compound made in an exact manner,

with exact proportions, under exact conditions and produces a material of exact chemical analysis with definite physical and chemical properties which are of definite commercial value. The other proportions of calcium used and the conditions employed by me in my experiments which were varied up to six equivalent atoms of calcium are not of definite value, or physical or chemical properties, to the best of my present knowledge. According to my experiments they gave anomalous acidities of low value, and indiand the tetraphosphoric acid probably under-' cated admixtures of ortho and pyro phosphate.

Their neutralizing value was 25% to of their weight of bicarbonate of soda which is notcommercially of value for most purposes. In my opinion ;the excess alkalinity and the heat of reaction, together, caused hydrolysis to take place went the change as follows:

The proportions vary probably in proportion to the amount of lime present and the temperatures. The lime then probably combines with these acids forming the above compounds.

The graphic formula of the acid calcium tetraphosphate can be probably indicated as follows:

' My reasoning for this formula is that the compounds tend to hydrolyze in alkaline solution, such, for instance, as an excess of lime and water,

to the pyrophosphates. Therefore this reaction, written graphically, would be:

The reaction as written out would be: cmmnouwcmom==zca=rloq+amo Probably the molecule splits in the center between the two interior phosphorus atoms and water is split oil. The 09.0 radical then enters where the molecule has splitand water is split oil each Ca(OH)z molecule. 1 have indicated the water molecules splitting off by the dot and dash lines in the diagram.

As indicated above, my researches indicated that a perfectly satisfactory product may be made from the commercially available tetraphosphate containing the pyropho'sphate impurity, which my analyses indicate is present in about man The physical properties of the pyrophosphate and the tetraphosphate acid calcium salts are practically identical, and any slight diflerence resulting from such a small admixture as 17%% would not be noticed and would be immaterial.

In my research I have used quick lime (CaO) to neutralize the tetraphosphoric acid, but by' modifying the conditions of the reaction slightly I can make my acid calcium'tetraphosphate from hydrated or slaked lime (CaOzH-n or from calcium carbonate (CaCOa) as well as from the quick lime (GaO) as-they are interchangeable where calcium is to be added to an acid, all neutralizing the acid by introducing the calcium atom into the molecule, their activity being in the order named. The reactions would be:

I have given the formula of my acid calcium tetraphosphate as CaaHzPaOr: but it should be noted that the material crystallizes with live molecules of water of crystallization which may be driven off by heating. The reaction would be as follows:

CMHaP4Ou5EO+ heat "CSMAOlSfFSHIO,

mediate utilization in various combinations set new and useful results.

My experiments with my acid calcium tetraphosphate indicates that it is unexpectedly different from any calcium phosphates heretofore produced in character and performance.

What I therefore claim and desire to secure by Letters Patent is:-

Y 1. Acid calcium tetraphosphate having as an indicated formula CaaZiIzHOn.

2. Acid calcium .tetraphosphate having the property of neutralizing bicarbonate of soda.

3. White pulverulentacid calcium tetraphosphate having the property of neutralizing from approximately 25% up to approximately 66% of its own weight of bicarbonate of soda.

approximately 85%phosphoric anhydride, to se- 5 cure a white puiverulent substance.

5. A method of produeingfan'acid calcium tetraphosphate consisting in reacting 6.612 parts by weight of lime with 20 parts by weight of tetraphosphoric acid and containing approxi- 10 mately 85% phosphoric anlrvdrlde, to secure a. white puiverulent substance, and in drying and puiverizing the resulting product.

AUGUSTUS n. msxn. 15 

